Method of manufacturing containers



United States Patent Ofitice 3,162,310 Patented Dec. 22, 1964 3,162,310 METHOD OF MANUFACTURING CONTAINERS Robert D. Tiberiis, Newport, Arlc, assignor to Victor Industries Corporation, Greenwich, Conn., a corporation of New York No Drawing. Filed July 27, 1962, Ser. No. 213,008 1 Claim. (Cl. 207-) This invention relates to an improvement in the process of manufacturing extruded aluminum containers such as are used for pressure propelled products.

Aluminum containers of this type are usually formed by impact extrusion. In this process a blanked slug of metal is fed into the female die of an extrusion press. A plunger in the form of a male die is forced against the slug within the female die. The slug under tremendous pressure, is momentarily reduced to a molten state and forced to flow into the space between the plunger and the die and around the male die forming the body of the container. During this operation, a lubricant must be used to reduce friction arising between metal surfaces and to preserve the dies. After extruding, however, it is essential that all of the lubricant be removed since the containers must be free of lubricant to prevent contamination of the contents and to permit decorating the outside or coating the inside of the containers.

The removal of the lubricant from the containers has previously been achieved by washing the containers with solvents or strong detergents. The use of solvents, however, is unsatisfactory since it involves health hazards to employees. Many solvents are flammable and require special handling.

Where detergents are used for cleaning the containers, it is necessary to rinse the containers with water to remove the residue. The containers must thereafter be passed under jets of air to remove the adherent water. Although most of the water is removed, the containers are by no means dry and some moisture remains on them which is then allowed to dry prior to coating. During this drying period the moisture is in contact with the metal of the container and has a tendency to corrode or stain the metal surface. Substantial corrosion makes the containers unfit for commercial use and may interfere with subsequent decorating. Additional disadvantages of the washing procedure are that frequently traces of the lubricant remain on the surfaces and the wall of the containers may become discolored by the detergents and water.

An object of the present invention is to provide clear and uncontaminated metal containers.

Another object of the invention is to provide a special lubricant for the process of extruding containers.

Still another object of the invention is to provide the complete removal of the lubricant after the extrusion process without corroding or discoloring the said containers.

One further object of the invention is to provide the evaporation of the lubricant without affecting the hardness of the containers.

In carrying out the present invention, there is employed a composition having the characteristic of low boiling point and preferably comprising a mixture of alcohol, oil

and wax. This composition serves as a lubricant during the extruding process. Due to its low boiling point it may thereafter be removed merely by heating the containers in an oven until the lubricant evaporates completely. To prevent an undesirable annealing of the containers during the heating, the temperature of the oven and the time of heating must be regulated and controlled.

For aluminum, 600 F. is usually considered as the annealing temperature at which aluminum softens to a noticeable degree, but annealing can be observed even at a temperature of 300 F. when the heating is prolonged for 10 or 15 minutes. In the practice of the present invention the desired result can be obtained by subjecting the containers to a temperature between 500-550 F. for a period of time not exceeding two minutes. During this short period a complete evaporation of the lubricant described herein takes place without annealing the metal of the containers.

In order to illustrate this invention, but without being limited thereto, the following example is given.

Example A lubricant that may be used with this invention is one having the following composition:

The foregoing are mechanically mixed at ambient or room temperature to form a viscous solution.

Although the present invention has been described with reference to a particular embodiment thereof, it will be apparent to those skilled in the art that variations and modifications of this invention can be made and that equivalents can be substituted therefor without departing from the principles, and spirit of the invention.

The foregoing example will evaporate or boil off the surface of the containers upon the applicationof heat without leaving any residual ash, grease or other foreign material.

Having thus fully described the invention, what is claimed as new and desired to be secured by Letters Patent of the United States, is:

In the process of manufacturing impact extruded metal containers the steps of lubricating the work-piece with a lubricant having a boiling point lower than the annealing temperature of the metal, extruding the lubricated Workpiece and thereafter heating the extruded work-piece to a temperature, higher than the boiling point of the lubricant but lower than the annealing temperature of the metal, until a complete evaporation of the lubricant takes place.

References Cited in the file of this patent UNITED STATES PATENTS 2,151,285 Toussaint Mar. 21, 1939 2,350,570 Schilling et a1. June 6, 1944 2,356,367 Wright Aug. 22, 1944 2,411,032 Engelke et al Nov. 12, 1946 

